u/Heartachoke

The one I'm using right now I have to be really careful and guided to put it on because it dries and sets so fast on my skin that it's hard to tell just by feel if a spot is covered by sunscreen or not because the drydown feels so dry and there's no shine to it. So I've been using a UV camera to guide me applying it.

Over an hour, it starts to look different under the UV camera and keeps on changing. What does that mean? Instead of being completely dark, there are white streaks and patches that get bigger over time. Like I said in the title, I know we can't tell the amount of protection but why does it start to look different? Is there any meaning to that?